The present invention is related to battery operated illuminating devices, which in preferred embodiments are designed for illuminating the area surrounding a doorknob or lock and key hole. The desirability of illuminating the lock area while an individual is trying to unlock a door and enter a residence or place of business is well known. Equally well known is the use of various small illuminating devices that are attached to the door or built into the door and used for illuminating the lock area for a prescribed period of time.
The prior art reveals numerous patents directed to such devices. Some of the later ones include electronic time-delay circuits whereby an individual utilizes a switch to selectively connect an energy source to the lamp; the lamp is energized for a pre-set period of time; and when the preset period of time has expired, the time-delay circuit automatically de-energizes the lamp. Two patents which are known to include time-delay mechanisms are the ones to Bartick U.S. Pat. No. 3,590,234, and to Blank U.S. Pat. No. 4,293,894.
The Bartick patent discloses a small illuminating device that includes a vacuum cup controlled time-delay actuator. When an individual approaches the door on which the Bartick illuminating device is mounted, they must be able to exert sufficient pressure on the pushbutton to constrict the vacuum cup to allow the switch arm to make contact and operate the lamp. If the applied force is not sufficient to properly engage the vacuum cup, the timing can be erratic and it is possible to have to repeatedly activate the illuminating device before the lock is successfully opened. Additionally, the Bartick device is complex and thereby expensive to manufacture and prone to failure over a period of time.
The Blank U.S. Pat. No. 4,293,894 is directed to a timing circuit in an illuminating device; the timing circuit having a pre-set, non-variable time-delay means for energizing the lamp. The time-delay device is an integrated circuit which cannot be varied by the individual owner. If the pre-set time is not appropriate for the owner's particular requirements, there is no means for making adjustment absent the actual removal of various components and replacement with totally different component values. This is beyond the ability of most consumers. Additionally, the electronic circuit disclosed by Blank is in many instances inadequate to energize a lamp of sufficient illumination for enlarged areas.
The present invention is an improved battery operated illuminating device, operative by means of an electronic time-delay circuit which can be manually adjusted by the owner with ease. Although described herein as being battery powered, the illumination device may be connected to the building's central electrical system and the battery eliminated.
Additionally, the electronic circuit itself, whether of an adjustable or of a fixed time delay design, is an improved means for providing a time-delay circuit to other types of illuminating devices or small appliances. By means of the improved variable circuit, the time-delay means may be pre-set for a period of approximately nine to ninety seconds and adjusted as required by the individual owner. It may be reset to vary the time-delay circuit as needed. The alternate, fixed time-delay circuit is believed to be more efficient and economical to produce than known circuits. The specifics of both circuits are described in the detailed description that follows.
The illuminating device of the present invention includes in the preferred embodiment a relatively small housing having a first, opaque portion that houses and conceals the electronic circuit board and battery, and a second portion that is translucent and surrounds the lamp. The preferred housing is basically rectangular in shape and is attached to the door (or other surface adjacent the area to be illuminate) by means of screws or pressure sensitive material along an underside of the housing. The illuminating device is positioned on the door or other surface such that it is adjacent the lock and can be easily reached and activated by an individual who may frequently be carrying packages or other objects. The translucent portion is preferably most closely adjacent the lock, and the light emitted therethrough will illuminate the area for the predetermined time of approximately nine to ninety seconds after the switch is actuated. Because of the improved circuitry, a lamp of greater candle power than heretofore possible has been utilized. Thus, a much larger area of the surrounding door is illuminated. When the switch is activated to energize the lamp, the time delay circuit begins to function and at the end of the prescribed period of time de-energizes the lamp.
The objects of the present invention therefore include: the provision of an improved device for illuminating any small area such as the doorknob and key hole area of an entry; the provision of an electronic time-delay circuit which can be easily, manually adjusted by the owner to vary the preset time interval; the provision of an improved electronic, fixed or variable timing circuit for deenergizing the lamp after a predetermined prescribed time and the provision of a circuit sufficient to energize a lamp of at least 0.5 candle power.